Model Definition

Useful when considering situation without losing holistic viewpoint, example of modelling is boundary and environment diagram.
The type of model used should be the best suited based on our understanding of the situation.
A model is an abstraction of reality, to abstract is to summarise. Models are created because:

  • Real life is complex – not just black and white but many shades in between.
  • they help us understand situations by simplifying real life.

Humans make use of mental models – an internal picture of many things in life, particularly for routine activities. Models only updated by new information is received.
Mental models help us respond effectively e.g. when driving, the car in front brakes and slows down so we automatically react by applying our brakes.
Consideration has to be given to the level of abstraction applied to the model; too high a level and the model will be too simplistic, too low a level and the model might be too detailed and we may lose understanding of what is occurring.
“… the measure of success in modelling is not that you can produce a model that is bigger and more sophisticated than anyone else’s but that it adequately answers the original question for which it was developed”. Wilson (1984, p.7)
e.g valid model could be architects scale plan for house.
e.g. invalid  model(s) were those used to represent economic, credit rating and banking systems between 1990s and 2007. Models were very complex but failed to model all interconnections and contributed to disastrous results.
According to Stowell and West (1990), success of modelling rests upon skills of modeller and their ability to:

  • Understand the activity being modelled
  • Understand the nature and implications of different models
  • An ability to select these models for use in a meaningful way


  1. Stowell F.A, West D 1990, The contribution of systems ideas during the process of knowledge elicitation. In Systems Prospects, the next ten years of systems research. Flood et al Plenum Press New York
  2. Wilson B 1984 Systems: Concepts, Methodologies and applications, John Wiley 2nd ed, Chichester UK






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